Effect of Vaccination on Preventing Influenza-Associated Hospitalizations Among Children During a Severe Season Associated With B/Victoria Viruses, 2019–2020. (27th January 2021)

• Record Type: Journal Article
• Authors: Campbell, Angela P; Ogokeh, Constance; Weinberg, Geoffrey A; Boom, Julie A; Englund, Janet A; Williams, John V; Halasa, Natasha B; Selvarangan, Rangaraj; Staat, Mary A; Klein, Eileen J; McNeal, Monica; Michaels, Marian G; Sahni, Leila C; Stewart, Laura S; Szilagyi, Peter G; Harrison, Christopher J; Lively, Joana Y; Rha, Brian; Patel, Manish
• Is Part Of: Clinical infectious diseases. Volume 73:Number 4(2021)
• Page Start: e947
• Page End: e954
• Publication Date: 2021-01-27
• Subjects: influenza -- vaccination -- test-negative design -- children; Communicable diseases -- Periodicals; 616.905
• DOI: 10.1093/cid/ciab060
• Languages: English
• ISSNs: 1058-4838

Abstract

Abstract: Background: The 2019–2020 influenza season was characterized by early onset with B/Victoria followed by A(H1N1)pdm09 viruses. Emergence of new B/Victoria viruses raised concerns about possible vaccine mismatch. We estimated vaccine effectiveness (VE) against influenza-associated hospitalizations and emergency department (ED) visits among children in the United States. Methods: We assessed VE among children aged 6 months–17 years with acute respiratory illness and ≤10 days of symptoms enrolled at 7 pediatric medical centers in the New Vaccine Surveillance Network. Combined midturbinate/throat swabs were tested for influenza virus using molecular assays. Vaccination history was collected from parental report, state immunization information systems, and/or provider records. We estimated VE from a test-negative design using logistic regression to compare odds of vaccination among children testing positive vs negative for influenza. Results: Among 2029 inpatients, 335 (17%) were influenza positive: 37% with influenza B/Victoria alone and 44% with influenza A(H1N1)pdm09 alone. VE was 62% (95% confidence interval [CI], 52%–71%) for influenza-related hospitalizations, 54% (95% CI, 33%–69%) for B/Victoria viruses, and 64% (95% CI, 49%–75%) for A(H1N1)pdm09. Among 2102 ED patients, 671 (32%) were influenza positive: 47% with influenza B/Victoria alone and 42% with influenza A(H1N1)pdm09 alone. VE was 56% (95% CI, 46%–65%) for an influenza-related ED visit, 55% (95% CI, 40%–66%) for B/Victoria viruses, and 53% (95% CI, 37%–65%) for A(H1N1)pdm09. Conclusions: Influenza vaccination provided significant protection against laboratory-confirmed influenza-associated hospitalizations and ED visits associated with the 2 predominantly circulating influenza viruses among children, including against the emerging B/Victoria virus subclade. Abstract : In the New Vaccine Surveillance Network of 7 US pediatric medical centers, influenza vaccine effectiveness was 62% (95% confidence interval [CI], 52%–71%) and 56% (95% CI, 46%–65%) against influenza-related hospitalizations and ED visits, respectively, protecting against B/Victoria and A(H1N1)pdm09 viruses.